R/sn_get_city_streets.R

In giocomai/streetnamer: Match street names to their Wikidata identifier with a Shiny interface

#' Gets roads within city boundaries, crops them, and keeps only those with names
#'
#' This function downloads all roads for a given country, downloads boundaries for a given administrative unit, and removes roads with no names.
#'
#' @param gisco_id Gisco id of the municipality
#' @param lau_year Passed to `ll_get_lau()`. Defaults to 2020 for internal consistency.
#'
#' @return
#' @export
#'
#' @examples
sn_get_named_city_streets <- function(gisco_id,
                                      cache_names = FALSE,
                                      cache_sf = FALSE, 
                                      lau_year = 2020) {
  country_code <- stringr::str_extract(string = gisco_id, pattern = "[A-Z][A-Z]") %>%
    stringr::str_to_upper()
  city_code <- stringr::str_extract(string = gisco_id, pattern = "[[:digit:]]+")

  cached_file <- fs::path(
    sn_get_data_folder(),
    stringr::str_to_lower(country_code),
    "named_city_roads_sf",
    stringr::str_c(
      gisco_id,
      ".rds"
    )
  )

  if (fs::file_exists(cached_file)) {
    return(readRDS(cached_file))
  }

  if (country_code == "IT") {
    named_city_roads <- ll_osm_extract_it(
      level = "comuni",
      code = city_code
    ) %>%
      dplyr::filter(is.na(name) == FALSE, is.na(highway) == FALSE) %>%
      sf::st_intersection(y = latlon2map::ll_get_nuts_it(
        level = "lau",
        resolution = "high"
      ) %>%
        dplyr::filter(PRO_COM_T == city_code)) %>%
      dplyr::group_by(name) %>%
      dplyr::summarise()
  } else {
    country_full_name <- countrycode::codelist %>%
      dplyr::filter(iso2c == country_code) %>%
      dplyr::pull(iso.name.en)

    named_city_roads <- ll_osm_get_roads(country = country_full_name) %>%
      dplyr::filter(is.na(name) == FALSE, is.na(fclass) == FALSE) %>%
      sf::st_intersection(latlon2map::ll_get_lau_eu(year = lau_year) %>%
        dplyr::filter(GISCO_ID == gisco_id)) %>%
      dplyr::group_by(name) %>%
      dplyr::summarise()
  }

  if (cache_names == TRUE) {
    sn_write_lau_street_names(
      df = named_city_roads %>%
        sf::st_drop_geometry() %>%
        dplyr::transmute(gisco_id = gisco_id, name),
      type = "osm_lau_street_names",
      country = "it"
    )
  }

  if (cache_sf == TRUE) {
    fs::dir_create(fs::path(
      sn_get_data_folder(),
      stringr::str_to_lower(country_code),
      "named_city_roads_sf"
    ))

    named_city_roads %>%
      saveRDS(file = cached_file)
  }
  named_city_roads
}